Control device for electric alarms



Apri 1941. J. LEMIRE TAL 2,236,689

CONTROL DEVICE FOR ELECTRIC ALARMS Filed May 26, 1938 JOSEPH LEN/EE,HENB/LErv/RE 4I/V0 Foo oz. PHE LEM/EE Patented Apr. 1, 1941 CONTROLDEVICE FOR ELECTRIC ALARMS Joseph Lemire, Henri Lemire, and RodolpheLemire, Drummondville, Quebec, Canada, assignors of one-half to NorbertBoisvert, Drummondville, Quebec, Canada applicati@ May ze, 193s, serialNo. 210,218

1 Claim.

The present invention pertains to a novel device for controlling andgoverning the operation of an electric alarm.

The principal object of the invention is to provide such a deviceadapted to be mounted on a structural member that Vibrates when aforcible entry is attempted. Such a member may be, for example, a windowsash, window or door, or the frame or surrounding structure associatedwith a window or door. invention embodies a pair of contacts carried bythe vibratory member and governing the circuit to the alarm. One ofthese contacts is adapted to vibrate relatively to the other when thestructural member vibrates. The vibratory Contact is made relativelymovable by suitable means such as a vibratory support, a weight or both.Where a resilient support is used, the invention also employs means foradjusting the tension of the support.

In one form of the invention, the control device is enclosed in a casingcarried by the vibratory member and carrying one of the contacts. Theother contact is carried on a spring arm attached to but insulated fromthe casing. The arm is also weighted to introduce a difference ofinertia between the contacts, so that movement of the structural memberintroduces relative Vibration between the contacts, with the result thatthe alarm circuit is rapidly made and broken.

Ordinarily, the contacts are normally in engagement with each other, andthe alarm so constructed that it is idle in this condition but operateswhen the contacts separate. Obviously,

these conditions may be reversed, but in either case the alarm operateswhen one of the contacts vibrates relatively to the other.

The invention is fully disclosed by way of example in the followingdescription and in the accompanying drawing, in which Figure 1 is ahorizontal section, partly in elevation, of the device as applied tosolid window frames or walls;

Figure 2 is a vertical elevation thereof;

Figure 3 is a vertical section of a window sash,

i showing in elevation a modied form of the invention applied thereto;

Figure 4 is a section on the line 4-5 of Figure 3;

Figure 5 is an elevation of the upper end of the device shown in Figure3, and

Figure 6 is a detail, partly in section, of the lower end.

Reference to these views will now be made by In general, the device ofthe use of like characters that are employed to designate correspondingparts throughout.

In Figure l, the numeral l designates a structural member which may be aportion of a wall or window frame. In any case, it is a member that islikely to be subjected to vibration if a forcible entry is attempted.

The device includes a suitable bracket 2, conductive of an electriccurrent, to which is secured one end of a Very light piece of sheetmetal 3. The free end oi the member 3 is secured to the center of aweight 4 as shown more clearly at the numeral 5 in Figure 2. Theassembly is enclosed in a suitable casing 6 which is also conductive ofelectricity. The adjacent face of the weight 4 carries a contact Inormally engaging a pointed contact B on the inner wall of the casing.

'Ihe bracket 2 is insulated from the casing 6 by an insulating insert 9.This member and the metal piece 3 are secured to the bracket 2 by rivetsIU. The same rivets hold one end of a soft metal sheet II adapted toengage the member I. By adjusting the bend of this sheet, thedisplacement of the weight 4 can be regulated.

A conductor I2 is connected to the bracket 2 by a screw I3. Similarly,another conductor I4 is fastened to the casing 6 by a screw I5. Bothscrews extend into the member I and may serve to support other parts ofthe assembly as clearly illustrated in Figure 1.

A circuit is thus ma-de through the contacts I and 8 to an alarm. Thecontacts are normally in engagement with each other, and the alarm isone that is inoperative when these contacts are in engagement.

When a forcible entry is attempted at or near the member I, the latterwill be caused to vibrate. The weight 4 will also be set in vibrationbut at a slower rate because of its inertia. Consequently a separation,or repeated separations, of the contacts I and 8, will occur, openingthe circuit and operating the alarm.

The modification shown in Figures 3, 4, 5 and 6 is designed forapplication to a movable window frame or sash. The frame member 2!carries a screw 2l which, in turn, preferably carries a bushing 22. Wireconductors 23 and 24 are suspended from the screw, the member 23 carriesa weight 25 at its lower end, while the member 24 has its lower end bentand pointed at 26 and engaging in a socket 2T formed in the adjacentface of the weight 25. The upper ends of members 23 and 24 are woundaround an insulating sleeve 28 tted on the bushing 22, as shown moreclearly in Figure 4. Plates 29 and 30 are mounted on the sleeve 28 inengagement with the conductors 23 and 24 respectively and are held apartby an insulating disc 3l. coiled end of conductor 23, and suitablewashers 33 are mounted on the bushing 22 to take up the slack.

Conductors 33 and 35 are fastened to the plates 29 and 3l) respectively,whereby a circuit is made through the lower ends of the members 25 and26. When an attempt is made to force the Window open, the vibrationseparates the contacts 25 and 25 and thereby causes the alarm tooperate.

Bent plate 40 placed close to window frame 20 permits to regulate thecontacts by turning screw 2l. Plate Il@ engaging frame 20 at a pointoffset of the screw 2l causes the tilting of contacts 23 and 2li towardsthe glass forming part of member 2).

Although specific embodiments of the inven- A similar disc 32 engagesthe tion have been illustrated and described, it will be understood thatvarious alterations in the details of construction ,may be made withoutdeparting from the scope of the invention, as indicated by the appendedclaim.

What we claim ist l A control device for an electric alarm comprising-apair of contacts suspended from a relatively vibratory structure, one ofsaidcontacts being weighted and in contact with the other of saidcontacts whereby vibration of said structure breaks the circuit, a bentplate at the suspension ends of said contacts and adapted to engage saidstructure, and a screw passed through said suspension ends and adaptedto press said bent plate against the said structure in order to adjustthc tension of said contacts.

JOSEPH LEMIRE, HENRI LEMIRE. RODOLPHE LEMIRE.

